1. Field of the Invention
The present invention relates to a flat diamond drill for drilling openings in a glass plate, particularly a laminated glass for an automotive vehicle. Further, the present invention relates to a method of drilling an opening in a glass plate, particularly a non-circular opening, by using a flat diamond drill.
2. Description of the Prior Art
A diamond drill heretofore used for drilling an opening in a glass plate has a cutting blade or tip of a generally circular cross section. Such a prior art diamond drill is liable to be heated up to an extremely high temperature during drilling due to the difficulty of supplying a sufficient amount of coolant to the space between the cutting blade and the glass plate and due to the large area at which the cutting blade and the glass plate are held in contact with each other. This results in a difficulty of performing a desired drilling operation with efficiency. This is particularly true in case of drilling an opening in a laminated glass plate such as one having an interlayer of polyvinyl butyral.